The present invention relates to constant velocity joints, and more particularly, relates to a venting solution for constant velocity joints.
Constant velocity joints are common components in automotive vehicles. Typically, constant velocity joints are employed where transmission of a constant velocity rotary motion is desired or required. The common types of constant joints are a plunging tripod, a fixed tripod, plunging ball joint and a fixed ball joint. These types of joints currently are used in front wheel drive vehicles, rear wheel drive vehicles, and on the propeller shafts found in rear wheel drive, all-wheel drive and four wheel drive vehicles. The plunging constant velocity joints will allow for axial movement during operation without use of slip-spines, which sometimes initiate forces that result in vibration and noise. These constant velocity joints are generally grease lubricated for life and sealed by an elastomeric sealing boot when used on drive shafts. Thus, constant velocity joints are sealed in order to retain grease inside the joint while keeping contaminants and foreign matter, such as dirt and water, out of the joint. To achieve this protection the constant velocity joint is usually enclosed at the opened end by a sealing boot made of a rubber, thermoplastic or silicone. The opposite end of the outer race generally is enclosed by a dome or cap, known as a grease cap in the case of a xe2x80x9cdiscxe2x80x9d type of joint. A monoblock or integral stem and race design style joint is sealed by the internal geometry of the outer race. This sealing and protection of the joint is necessary because contamination of the inner chamber of the joint is undesirable.
During operation, the constant velocity joint creates internal pressures in the chamber of the outer joint. These pressures have to be vented to the outer atmosphere in order to prevent pressure build up which occurs during the operation of the joint and may affect the performance and life of the boot. If a pressure build up is allowed to reach a critical state within the boot, the boot may rupture or crack causing a loss of the seal. Generally speaking, a constant velocity joint is usually vented by placing a small hole in the center of the grease cap or at least one hole around the outer periphery of the outer race. These prior methods of venting pressure or gas are sometimes less effective because if the constant velocity joint is in the static state (not rotating) the lubricating grease may settle in the vent hole and block or hinder its function of venting any internal gas pressure. Furthermore, the constant velocity joint, after running for long periods of time, creates very high temperatures along with the high pressures. These high temperatures may be reduced by venting gas through the current vent holes. However, if the constant velocity joint is submerged or saturated in water or other contaminants, the water may, via vacuum, enter into the constant velocity joint thus contaminating the grease lubricant and possibly reducing the life of the constant velocity joint. Therefore, the ingress of water and other contaminants through the vent hole may reduce life expectancy of the constant velocity joint.
Therefore, there is a need in the art for a constant velocity joint that is able to vent the internal pressure gas build-up while keeping contaminants from entering the constant velocity joint through the venting mechanism.
An object of the present invention is to provide a venting solution for a constant velocity joint.
Yet a further object of the present invention is to provide a vent for a constant velocity joint that has a permeable membrane to the atmosphere.
Yet a further object of the present invention is to prevent the entry of contaminants into the constant velocity joint internal chamber while allowing the venting of pressurized gas from the inside of the constant velocity joint chamber.
Yet a further object of the present invention is to provide a vent for a constant velocity joint with minimal increase in cost and manufacturing time.
To achieve the foregoing objects the constant velocity joint for use in a vehicle includes an outer race. The constant velocity joint also includes an inner race supported within the outer race. The constant velocity joint further includes a cover wherein that cover creates a barrier between a lubricant and the atmosphere. The constant velocity joint also includes a permeable membrane adjacent to the cover.
One advantage of the present invention is that the constant velocity joint includes a vent that has a permeable membrane to the atmosphere.
A further advantage of the present invention is that the constant velocity joint vent system allows gas, which is under pressure, to escape from the internal joint chamber to the atmosphere and allows gas to enter from the atmosphere to the internal chamber.
A further advantage of the present invention is providing constant velocity joint vent will stop the entry of contaminants into the constant velocity joint.
Other objects, features and advantages of the present invention will become apparent from the subsequent description and appended claims, taken in conjunction with the accompanying drawings.